BME 203 Exam 3 Review

Approximately how much surface area does the endoplasmic reticulum have compared with the plasma membrane of a typical mammalian cell?

About 20-30 times as much

What membrane structure gave rise to the nuclear envelope?

Plasma membrane infolding sthat surrounded the DNA

What happens when a protein's nuclear localization signal (NLS) becomes exposed?

A nuclear import receptor can recognize the protein

In what order does a glycoprotein pass through the compartments during processing

ER -> cis Golgi -> central Golgi -> trans Golgi

What does endosomal acidification normally do to the LDL-LDL receptor complex?

It separates LDL from the receptor, allowing the receptor to recycle

A protein co-sediments with an organelle. It resists added protease when the organelle is intact but is digested after detergent is added. Where is the protein most likely located?

Inside the organelle lumen

Which property helps determine both the signals a cell detects and how strongly it responds?

The types and amount of receptors the cell expresses

What happens if Ga hydrolyzes GTP more slowly after acetylcholine activates its receptor in a heart pacemaker cell?

Ion channel activations last longer

Which enzyme hydrolyzes cAMP to AMP?

cAMP phosphodiesterase

Which enzyme does nitric oxide activate in neighboring smooth muscle cells to increase cGMP and promote relaxation?

Guanylyl cyclase

How does activated Akt promote cell survival through Bad and Bcl2?

It phosphorylates Bad, releasing Bcl2 from inhibition

Which enzyme can be activated downstream of both GPCRs and receptor tyrosine kinases to trigger intracellular calcium release

Phospholipase C

Constitutively active Ras restores signaling when protein X is inactive. Where does protein X act relative to Ras?

Upstream of Ras

What should researchers compare an organ-chip model's predictions against to assess accuracy for its intended use?

Relevant human reference data

Which approach best tests whether a liver chip reproducibly predicts drug-induced liver injury?

Repeat the test across devices, independent experiments, and laboratories.

What structure forms when two intermediate filament dimers associate in a staggered, antiparallel arrangement?

A tetramer

What is the name for a microtubule's ability to switch between growth and rapid shrinkage?

Dynamic instability

What happens when calcium binds to troponin in skeletal muscle?

Tropomyosin shifts and exposes myosin-binding sites on actin

How do fibroblasts organize secreted collagen fibrils into sheets or cables?

They attach to the fibrils and pull on them

Which extracellular adhesive protein links collagen to cell-surface integrins?

Fibronectin

How do negatively charged glycosaminoglycans (GAGs) help cartilage resist compression?

They attract cations and draw water into the matrix

Which surface of an epithelial cell faces a lumen or the external environment?

Apical surface

Which junction restricts the passage of water-soluble molecules between neighboring epithelial cells?

Tight junction

Which extracellular ion is required for cadherin-mediated homophilic binding?

Calcium (Ca^2+)

Which cytoskeletal network do adherens junctions connect across neighboring cells?

Actin filaments

Which transmembrane proteins in hemidesmosomes bind laminin in the basal lamina?

Integrins

Which tissue interface does the lung-on-a-chip recreate?

The alveolar-capillary interface between lung airspaces and blood vessels

How does the lung-on-a-chip cyclically stretch its tissues to mimic breathing?

It applies and releases a vacuum in the side chambers

Which fabrication method was used to create recessed microchannels in the lung chip's PDMS layers

soft lithography

Which pair of junctional proteins was observed at cell-cell contacts in the lung chip?

Occludin and VE-cadherin

Which endothelial adhesion molecule increases in response to inflammatory cytokines and helps recruit circulating immune cells?

ICAM-1

What did the recruited neutrophils do after crossing the alveolar-capillary barrier in the bacterial challenge experiment?

They engulfed bacteria

How did the underlying vascular endothelium respond when the alveolar side of the chip was exposed to silica nanoparticles?

It became activated and increased ICAM-1 expression

What happens to cAMP production if an activated Ga subunit cannot hydrolyze GTP?

It continues longer than usual